I'm doing some computer graphics and I'm pretty new to physics/mechanics. Right now I'm simulating a pendulum. But now I want to be able to move the pendulum to, the point to which the string is connected (for instance if I hold the pendulum between my fingers and move my hand). Now which forces are acting on the pendulum now, how can I update it's position? I'm simulating everything with a computer, so I want the movements to be arbitrary.